DESCRIPTION (Adapted from applicant's description): Antibodies against specific pathogens to which the mother has been exposed are found in human milk, and in many cases they protect the infant from these pathogens. More recently, non-antibody components, especially glycoconjugates, have been found to inhibit several pathogens, including enteric pathogens. The investigator has found previously unrecognized sulfated glycolipids in human milk. Preliminary studies have demonstrated that this sulfated glycolipid fraction inhibits key pathogenic processes associated with infection by Salmonella and HIV. The purpose of this proposal is to define the molecular species of sulfated glycolipids that are responsible for each of these inhibitory activities. The specific aims are: (1) the purification of individual sulfated glycolipid species from human milk using a combination of state-of-the-art chromatographic procedures; (2) the identification and unambiguous characterization of those species that are biologically active against Salmonella typhimurium; (3) elucidation of mechanisms whereby these sulfated glycolipid species affect specific pathogenic processes of Salmonella typhimurium infection; (4) identification and unambiguous characterization of purified sulfated glycolipid species that are active against HIV.